On 17/01/2013 16:36, Jonathan wrote:
On Jan 17, 4:14 pm, Nightjar
....
I don't have air bricks but I do have a ground floor shower that water
might come through the drain. I haven't yet found the thing to block
that. Any ideas.

A length of steel pipe, larger ID than the OD of the drain, with a
flange on the bottom and a flexible seal on the flange? The weight of
the pipe should hold it in place while the water simply rises inside it.

Colin Bignell